Hermetically sealed multitrimmer potentiometer



March 12, 1968 R. w. SARGENT 3,373,395

HERMETICALLY SEALED MULTI-TRIMMER POTENTIOMETER Filed Aug. 1, 1967 IFIGL.

INVENTOR RAYMOND SARGENT ATTORNEY United States Patent 3,373,395 HERMETICALLY SEALED MULTI- TRIMMER POTENTIOMETER Raymond W. Sargent, Yorktown Heights, N.Y., assignor to Simmonds Precision Products, Inc., Tarrytown, N.Y., a corporation of New York Filed Aug. 1, 1967, Ser. No. 657,640 2 Claims. (Cl. 338-464) ABSTRACT OF THE DISCLOSURE A sub-miniature multi-turn potentiometer mounted to a solderable metal housing containing a hermetically sealed bent shaft mechanically coupled by means of a crank to the multi-turn potentiometer for adjusting the same within an air-tight environment.

This invention relates to potentiometers and, more particularly, to multiturn trimmer potentiometers of the type disclosed in Patent No. 3,058,080, issued to Laubenfels, and Patent No. 3,099,809, issued to V. G. Mathison et al.

Generally, multi-turn trimmer potentiometers comprise a single-turn circular resistance element disposed with its member encircling an axis about Which a contact carrying slider is moved along the periphery of the resistance element by rotation of a worm in mesh with a worm gear. With the present state of electronics placing a premium on both miniaturization and sensitivity, that is, accuracy of adjustment, it is desirable that such multi-turn potentiometers be hermetically sealed from the atmosphere in an improved manner from that disclosed in applicants Patent No. 3,184,697, issued May 18, 1965.

Accordingly, it is an object of this invention to provide a multi-turn trimmer potentiometer which is completely sealed in a true hermetic enclosure from the surrounding atmosphere without sacrificing miniaturization and sensitivity of adjustment.

It is another object of this invention to provide an integrated unit which consists of a commercially available sub-miniature multi-turn trimmer potentiometer mounted to a solderable adjustment unit for replacing the conventional rotary hermetic seals and associated trimmer potentiometers.

Briefly, the invention comprises a sub-miniature multiturn trimmer potentiometer mounted to a solderable metal housing containing a hermetically sealing orbital metal bellows assembly mechanically coupled by means of a crank and T-bar arrangement to the multi-turn pottentiometer.

Further objects and advantages of this invention will become apparent from a further reading of the specification and drawings in which:

FIG. 1 is a partial sectional View of the device according to this invention; and

FIG. 2 is a composite front and side detail view of the hermetically sealed multi-turn potentiometer in a mounted position.

Referring now to FIG. 1, the multi-turn potentiometer 2 is a miniaturized commercially available model constructed in a known manner to those skilled in the art. According to the principles of this invention, the potentiometer 2 is provided with an adjustment shaft 4 in the form of a T-bar, as shown. Mounted to the potentiometer 2 is a filler member and a solderably cylindrical metal housing 6 which has soldered to its internal flange a flexible metal bellows 8, the opposite end of which has a pin 10 soldered thereto for providing an air-tight flexible chamber. A bent shaft 12 is rotatably mounted to the top of the cylindrical housing 6 and a suitable snapretaining ring 14 is interposed between an outer flange of the 3,373,395 Patented Mar. 12, 1968 housing 6 and the collar portion of the shaft 12, as shown, to secure the shaft 12 in its mounted position. The inner end of the shaft 12 is provided with a bore centrally located therein for rigidly receiving one end of the pin 10 by means of running fit. The other end of the pin 10 bears against a portion of the T-bar 4. A slit in the outer end of the shaft 12 is provided for engagement with a screwdriver or the like so that the shaft may be rotated.

In FIG. 2, there is shown the integrated unit which can be manufactured in standard resistance ratings with provisions for the screwdriver adjustment at one end and the flexible leads or terminals at the other end of the device. The outside cylindrical portion of the housing may also have a tin surface suitable for soft soldering when mounted as shown.

In operation the multi-turn potentiometer 2 may be adjusted by rotating the bent shaft 12, which causes the outer end of the pin 10 to bear against the T-bar shaft 4 and rotating the same for a required adjustment. Thus, a multi-turn potentiometer 2, which is constructed according to this invention, may be adjusted in a hermetically sealed environment by means of rotary motion transmitted by the bent shaft 12 through the swiveling flexible metal bellows 8 to the T-bar shaft which, in turn, rotates a suitable contact carrying slider along the length of a circular wound resistance within the potentiometer 2.

Although only a single embodiment of the invention has been depicted and described, it will be apparent that this embodiment is illustrative in nature and that a number of modifications in the apparatus and variations in its end use may be effected without departing from the spirit or scope of the invention as defined in the appended claims.

That which is claimed is:

1. In a multi-turn potentiometer having a circular wound resistance and a rotatably mounted T-bar rotor adjustment member extending therefrom, a solderable metal housing mounted on said potentiometer and enclosing said T-bar member, a bent shaft member extending into said housing in one end thereof, said shaft member having an outer end portion substantially coaxial with said housing and having an inner end portion offset with respect to the axis of said housing, said outer end portion of said shaft member being rotatably mounted on said housing and having an inner end portion offset with respect to the axis of said housing, said outer end por tion of said shaft member being rotatably mounted on said housing and having means positioned thereon for rotating said inner end portion of said shaft member freely about the axis of said housing, a fluid-tight bellows member of flexible metal disposed about said shaft member from said one end of said housing to said inner end portion of said shaft member, said bellows member being bonded about the periphery of one end thereof to said housing member in hermetically sealed relationship therewith adjacent said one end of said housing, the other end of said bellows member being sealed inwardly of said housing from the inner end portion of said shaft member and cooperating with said housing to provide a hermetic seal, and a pin member in sealing engagement with said other end of said bellows extending from the inner end of said shaft ,member and engaging said T-bar member, whereby said T-bar member is rotated by rotation of said shaft member about the axis of said housing.

2. In a multi-turn potentiometer having a rotatably mounted T-bar rotor adjustment member extending from said potentiometer, a solderable metal housing mounted in an offset relation on said potentiometer and enclosing said T-bar member, a bent shaft member extending into said metal housing in one end thereof, said shaft member having an outer end portion substantially coaxial with said housing and having an inner end portion offset with respect to the axis of said housing, said outer end portion of said shaft member being rotatably mounted on said housing and having means positioned thereon for rotating said inner end portion of said shaft member freely about the axis, of said housing, a fluid-tight bellows member of flexible material disposed about said shaft member from said one end of said housing to said inner end portion of said shaft member, said bellows member being bonded about the periphery of one end thereof to said housing member in hermetically sealed relationship therewith adjacent said one end of said housing, the other end of said bellows member being sealed inwardly of said housing from the inner end portion of 4- to provide a hermetic seal and a pin member extending from the inner end of said shaft member and engaging said T-bar member, whereby said T-bar member is retated by the rotation of said shaft member about the axis of said housing.

References Cited UNITED STATES PATENTS 2,854,536 9/1958 Beer 200-168 3,099,809 7/1963 Mathison et a1 338143 3,184,697 5/1965 Sargent 338164 X 3,248,678 4/1966 Remus 338164 ROBERT K. SCHAEFER, Primary Examiner.

said shaft member and thus cooperating with said housing 15 HOHAUSER, Assistant Examiner- 

